Powder feeder with rotary, axially movable flow controller



W. A. CURRIE Sept. 3, 1968 POWDER FEEDER WITH ROTARY AXIALLY MOVABLE FLOW CONTROLLER 2 Sheets-Sheet 1 Filed Sept. 28, 1966 Sept. 3, 1968 w. A. CURRIE 3,399,814

POWDER FEEDER WITH ROTARY AXIALLY MOVABLE FLOW CONTROLLER Filed Sept. 28, 1966 2 Sheets-Sheet 2 United States Patent 3,399,814 -POWDER FEEDER WITH ROTARY, AXIALLY MOVABLE FLOW CONTROLLER William Albert Currie, Greenlord, Ealing, London, England, assignor to Messrs. Berk, Limited Filed Sept. 28, 1966, Ser. No. 582,569 Claims priority, application Great Britain, Sept. 28, 1965, 41,245/65 4 Claims. (Cl. 222--549) ABSTRACT OF THE DISCLOSURE A powder feeding device includes a hopper having a bottom opening provided with a valve seat. A conical valve member coaxial with the valve seat is provided with a depending axially bored valve stem slida'bly coaxially supported in a sleeve and delineating a vertical passageway therewith, the top of the sleeve being provided with a bottom stop for the valve and being vertically adjustable. The bottom of the stem is connected to a source of compressed air and the stem is provided with an outlet port between its ends to permit the flow of air between the tube and sleeve to prevent the deposit of powder therein.

This invention relates to a powder feeding device.

An object of the invention is to provide such a device for use with flame spraying equipment for spraying metal, plastics, ceramic powders and the like, the device having an outlet from a powder container which can be opened or closed in a simple manner and yet permits the rate of discharge of powder through the outlet to be adjustably pre-set as desired.

According 'to the invention, a powder feeding device comprises a container for powder, an outlet opening leading from the container, a valve which can be opened to permit the discharge of powder from the container or closed to terminate such discharge, and a flow rate control member the setting of which is adjustable to determine the area of the outlet opening and hence the rate of discharge of powder.

The valve can conveniently be a conical member movable to and from a valve seating provided at said outlet opening, and a pre-determined fixed point. In operation of the device it will be in either one of these positions, namely at the valve seating thereby closing the outlet opening of the powder container, or at a fixed point from the valve seating which is preselected as the fully open position allowing powder to escape from said outlet end without exerting a controlling effect upon the rate of powder discharge from the container. A flow-rate control member is arranged either above or below the on/off valve, coaxially therewith, and can be moved up and down with respect to the on/ofi valve independently of it.

When the device is in use, the position of the flow rate control member is set to give the required rate of discharge of powder from the container. The on/off valve is moved to its fully open position thus allowing powder to fall freely through the outlet aperture at a rate determined by the position of the flow rate control member.

In the accompanying drawings:

FIGURE 1 is a diagram illustrating a powder feeding device according to the invention,

FIGURE 2 is a sectional view of a modification.

In the embodiment of the invention illustrated in FIG- URE 1, a device for controlling the supply of powder to powder spraying equipment comprises a powder outlet tube 1 which leads out of the bottom of a container 2 for powder. This outlet tube 1 has a cylindrical valve Cir seat 3 at its lower end defining an outlet aperture for the powder.

A valve stem or needle 4 forms the on/off valve and is arranged beneath the outlet tube 1 and is coaxial with it. The upper end portion 5 of the needle or valve stem 4 is of conical shape and can enter the outlet aperture of the outlet tube 1. The diameter of the lower end of the conical end portion 5 is greater than that of the remainder of the stem 4 to provide a shoulder or abutment 6 for a purpose to be described. The valve stem 4 can be moved up and down with respect to the outlet aperture. When the valve stem 4 is in its uppermost position, the conical end portion 5 is engaged with the periphery of the valve seat 3, thereby to close the outlet aperture. When the valve stem 4 is at a lower position, powder can pass through the outlet aperture.

The lower end portion 7 of the valve stem 4 is screwthreaded and is screwed into a connecting nut 8 in a fixed part-9 of the device. The valve stem can therefore be raised and lowered by rotation in the nut thereby to open or close the outlet aperture. A control knob or wheel 10 is provided to rotate the valve stem 4.

The valve stem 4 is surrounded by, and is movable within, a valve control sleeve 11. This sleeve has an external screw thread 12 engaged in the co-operating fixed part 9 of the device so that the position of the sleeve 11 can be adjusted with respect to the lower end of the conical end portion 5 and bottom of the needle 4. The upper part of the sleeve 11 passes through a suitable gland or packing 13 and the top of the sleeve has a fiow rate control member 14 which can engage the lower shoulder 6 of the conical portion 5 of the valve stem 4. The position of the flow rate control member 14 of the sleeve 11 therefore determines the lower limit of movement of the needle 4, the upper limit being determined by the valve seat 3 of the outlet tube 1. Thus, although the outlet aperture is opened or closed by movement of the valve stem 4, the rate of discharge of powder is determined by the setting of the valve control sleeve 11. The largest area between the conical portion 5 of the valve stem 4 and the valve seat 3 will be possible when the flow rate control member 14 and sleeve 11 are at their lowermost position and the smallest area will be when the flow rate control member 14 and sleeve 11 are at their uppermost position.

FIGURE 2 illustrates a modification in which the valve stem or needle 4 is hollow and contains a co-axial air supply tube 15. One end of the tube 15 leads to an air outlet aperture 16 in the wall of the needle or stem 4 and the other end leads into an air connector union 17 provided with a ripple 18 receiving a hose 19 by which air under pressure can be supplied to the air tube 15. Air will pass from the tube 15 through aperture 16 between stem or needle 4 and the valve control sleeve 11 and then flow out between the ends of the sleeve and the stem or needle. This arrangement prevents powder becoming packed between the stem or needle and the sleeve. Powder which has discharged from the tube 1 will leave the device through an outlet union 20.

In a further embodiment of the invention, a modified flow rate control member has a frusto-conical shaped upper end and supported on a stern of smaller diameter than the largest diameter of the frusto-conical shaped end. This control member is interposed coaxially between the on/off valve and the outlet aperture for the powder. The largest diameter of the flow rate control member is such as to allow the member to enter the outlet aperture without resulting in closure of said aperture. By raising or lowering the member it is possible to vary the area between the outlet end of the powder container and the control member, and consequently to pre-select and set the 3 size of the 'outlet aperture in order to obtain a desired flow rate for the powder.

The stem of the flow rate control member is surrounded by, and is movable within, a valve control sleeve. This sleeve has an external screw thread engaged in a cooperating fixed part of the device so that the position of the sleeve can be adjusted with respect to the top and bottom of the stern of the flow rate control member. The upper part of the sleeve passes through a suitable gland or packing and the top of the sleeve has an annular plate the diameter of which is greater than that of the outlet end of the powder container. Said plate acts as the on/ oil valve since it is adapted to close the outlet end of the powder container when in contact therewith. If desired the on/off valve may comprise a cup-shaped member which is capable of closing the outlet aperture of the powder container but at the same time is able to house the frusto-conical upper end of the flow rate control member.

In operation the flow rate control member is raised or lowered until the desired outlet aperture is obtained, the on/off valve is then lowered by means of the valve control sleeve, ensuring that it is low enough to avoid imperance of powder flowing out from the outlet aperture. When the spraying operation is completed the on/off valve is raised to the closed position, and the device may then be re-used at will for similar coating operations without need for adjusting the flow rate control member.

What I claim is:

l. A powder feed device comprising a powder source having an outlet opening, a valve seat registering with said opening an axially linearly movable valve stem coaxial with said valve seat and provided with an axial bore having an outlet opening between its ends and an inlet opening, a tapered valve member mounted on an end of said stem and movable therewith toward and away from said valve seat, a longitudinal sleeve coaxially engaging said stem and defining a, linearly extending air passageway therewith and provided with a valve stop end portion confronting said valve member, means for axially adjusting said sleeve to limit the axial movement of said valve member from said valve seat and control the open position thereof, and means for connecting said bore inlet opening to a source of compressed air whereby air flows through said stem bore and the space between said stem and said sleeve.

2. The powder feed device of claim 1, wherein the end of said stem remote from said valve member is threaded and including an axially movable control member provided with a tapped bore engaging said stem threaded end.

3. The powder feed device of claim 1, wherein said valve member has a conical face.

4. The powder feed device of claim 1 wherein said sleeve includes an externally threaded section and said adjusting means includes an internally threaded member engaging said externally threaded section.

References Cited UNITED STATES PATENTS 1,393,615 10/1921 Foltz 251285 X 2,010,088 8/1935 Kohler 25l285 X 2,119,643 6/1938 Mendl 222549 X 2,180,468 11/1939 Hochstim 222-549 X 2,761,647 9/1956 Zeck 251-285 X SAMUEL F. COLEMAN, Primary Examiner. 

